skaffold docker deployer recreates new skaffold-* network every run w/o cleaning up old networks -> run out of docker networks over time

Currently the skaffold docker deployer creates a skaffold- network each run but does not clean it up during Cleanup/deletion. This means over time these skaffold networks increase monotonically until a user gets the error:
```
could not find an available, non-overlapping IPv4 address pool among the defaults to assign to the network
```

We should change the docker deployer to cleanup the network or reuse a constant network